improve datetime support

 - reduce date(time) false positive parsing
 - add option to disable raw datetime literals

Fixes #276

lib/dentaku/calculator.rb

@@ -10,7 +10,7 @@ module Dentaku
   class Calculator
     include StringCasing
     attr_reader :result, :memory, :tokenizer, :case_sensitive, :aliases,
-                :nested_data_support, :ast_cache
+                :nested_data_support, :ast_cache, :raw_date_literals
 
     def initialize(options = {})
       clear
@@ -19,6 +19,8 @@ def initialize(options = {})
       @aliases = options.delete(:aliases) || Dentaku.aliases
       @nested_data_support = options.fetch(:nested_data_support, true)
       options.delete(:nested_data_support)
+      @raw_date_literals = options.fetch(:raw_date_literals, true)
+      options.delete(:raw_date_literals)
       @ast_cache = options
       @disable_ast_cache = false
       @function_registry = Dentaku::AST::FunctionRegistry.new
@@ -94,9 +96,10 @@ def ast(expression)
 
       @ast_cache.fetch(expression) {
         options = {
+          aliases: aliases,
           case_sensitive: case_sensitive,
           function_registry: @function_registry,
-          aliases: aliases
+          raw_date_literals: raw_date_literals
         }
 
         tokens = tokenizer.tokenize(expression, options)

lib/dentaku/token_scanner.rb

@@ -7,7 +7,7 @@ module Dentaku
   class TokenScanner
     extend StringCasing
 
-    DATE_TIME_REGEXP = /\d{2}\d{2}?-\d{1,2}-\d{1,2}( \d{1,2}:\d{1,2}:\d{1,2})? ?(Z|((\+|\-)\d{2}\:?\d{2}))?/.freeze
+    DATE_TIME_REGEXP = /\d{2}\d{2}?-\d{1,2}-\d{1,2}( \d{1,2}:\d{1,2}:\d{1,2})? ?(Z|((\+|\-)\d{2}\:?\d{2}))?(?!\d)/.freeze
 
     def initialize(category, regexp, converter = nil, condition = nil)
       @category  = category
@@ -75,7 +75,9 @@ def scanners=(scanner_ids)
 
       def scanners(options = {})
         @case_sensitive = options.fetch(:case_sensitive, false)
-        @scanners.values
+        raw_date_literals = options.fetch(:raw_date_literals, true)
+
+        @scanners.select { |k, _| raw_date_literals || k != :datetime }.values
       end
 
       def whitespace

lib/dentaku/tokenizer.rb

@@ -4,7 +4,7 @@
 
 module Dentaku
   class Tokenizer
-    attr_reader :case_sensitive, :aliases
+    attr_reader :aliases
 
     LPAREN = TokenMatcher.new(:grouping, :open)
     RPAREN = TokenMatcher.new(:grouping, :close)
@@ -15,10 +15,14 @@ def tokenize(string, options = {})
       @aliases = options.fetch(:aliases, global_aliases)
       input    = strip_comments(string.to_s.dup)
       input    = replace_aliases(input)
-      @case_sensitive = options.fetch(:case_sensitive, false)
+
+      scanner_options = {
+        case_sensitive: options.fetch(:case_sensitive, false),
+        raw_date_literals: options.fetch(:raw_date_literals, true)
+      }
 
       until input.empty?
-        scanned = TokenScanner.scanners(case_sensitive: case_sensitive).any? do |scanner|
+        scanned = TokenScanner.scanners(scanner_options).any? do |scanner|
           scanned, input = scan(input, scanner)
           scanned
         end

spec/calculator_spec.rb

@@ -22,6 +22,7 @@
     expect(calculator.evaluate('(2 + 3) - 1')).to eq(4)
     expect(calculator.evaluate('(-2 + 3) - 1')).to eq(0)
     expect(calculator.evaluate('(-2 - 3) - 1')).to eq(-6)
+    expect(calculator.evaluate('1353+91-1-3322-22')).to eq(-1901)
     expect(calculator.evaluate('1 + -(2 ^ 2)')).to eq(-3)
     expect(calculator.evaluate('3 + -num', num: 2)).to eq(1)
     expect(calculator.evaluate('-num + 3', num: 2)).to eq(1)
@@ -445,6 +446,13 @@
     expect(calculator.evaluate('t1 > 2017-01-02', t1: Time.local(2017, 1, 3).to_datetime)).to be_truthy
   end
 
+  describe 'disabling date literals' do
+    it 'does not parse formulas with minus signs as dates' do
+      calculator = described_class.new(raw_date_literals: false)
+      expect(calculator.evaluate!('2020-01-01')).to eq(2018)
+    end
+  end
+
   describe 'supports date arithmetic' do
     it 'from hardcoded string' do
       expect(calculator.evaluate!('2020-01-01 + 30').to_date).to eq(Time.local(2020, 1, 31).to_date)